JPWO2020039695A1 - A liquid crystal alignment agent, a liquid crystal alignment film, a liquid crystal element, and a method for manufacturing a liquid crystal element. - Google Patents

Abstract

The polymer component and the cyclic siloxane compound [A] having a crosslinkable group are contained in the liquid crystal alignment agent. One aspect of the cyclic siloxane compound [A] is a compound represented by the formula (1). In the formula (1), R1 to R6 are independently hydrogen atoms or monovalent organic groups having 1 to 20 carbon atoms. However, at least one of R1 to R6 is a monovalent organic group having a crosslinkable group. n is an integer of 1-18. When n is 2 or more, the plurality of R1s may be the same or different from each other, and the plurality of R2s may be the same or different from each other.

Description

Cross-reference of related applications

This application is based on Japanese Application No. 2018-157299 filed on August 24, 2018, the contents of which are incorporated herein by reference.

The present disclosure relates to a liquid crystal alignment agent, a liquid crystal alignment film, a liquid crystal element, and a method for manufacturing a liquid crystal element.

The liquid crystal element includes a liquid crystal alignment film having a function of orienting liquid crystal molecules in the liquid crystal layer in a certain direction. The liquid crystal alignment film is generally formed on the substrate by applying a liquid crystal alignment agent in which the polymer component is dissolved in an organic solvent to the surface of the substrate and preferably heating the substrate.

In recent years, large-screen, high-definition liquid crystal televisions have become the mainstream, and small display terminals such as smartphones and tablet PCs have become widespread, and the demand for higher quality liquid crystal elements has increased more than before. Therefore, conventionally, various liquid crystal alignment agents have been proposed in order to improve the performance of the liquid crystal alignment film and to improve various characteristics of the liquid crystal element (see, for example, Patent Documents 1 to 3).

Patent Document 1 describes an epoxy compound having a nitrogen atom together with polyimide (for example, N, N, N', N'-tetraglycidyl-4,4'-diaminodiphenylmethane, 1,3-bis (N, N'-). Diglycidylaminomethyl) cyclohexane, etc.) is disclosed in the liquid crystal alignment agent. Further, Patent Document 2 contains a compound containing an imide bond and two or more epoxy groups (for example, monoallyl diglycidyl isocyanuric acid, triglycidyl isocyanuric acid, etc.) in the liquid crystal alignment agent together with polyamic acid or polyimide. It is disclosed to let you. Patent Document 3 discloses that the liquid crystal alignment agent contains a polyfunctional epoxy compound having two or more 3,4-epoxycyclohexane rings together with the polyamic acid or polyimide.

Japanese Unexamined Patent Publication No. 10-333153 JP-A-2007-139949 Japanese Unexamined Patent Publication No. 2016-170409

Liquid crystal elements are not only used in display terminals such as personal computers as in the past, but also indoors and outdoors such as LCD TVs, car navigation systems, mobile phones, smartphones, information displays, phase difference films, and dimming films. It is used in a wide variety of applications regardless of. Further, as the usage is expanded, it is expected that the liquid crystal element will be used in a harsher environment than before. Specifically, the liquid crystal element may be backlit for a long time due to continuous driving for a long time, used in a high temperature environment, or exposed to a high heat environment. On the other hand, the demand for higher performance of liquid crystal devices is further increasing, and it is required that the device performance can be maintained even under harsh environmental conditions.

The present disclosure has been made in view of the above circumstances, and its main purpose is to provide a liquid crystal display agent capable of obtaining a liquid crystal element having excellent light resistance and heat resistance.

According to the present disclosure, the following means are provided.
[1] A liquid crystal alignment agent containing a polymer component and a cyclic siloxane compound [A] having a crosslinkable group.
[2] A liquid crystal alignment film formed by using the liquid crystal alignment agent of the above [1].
[3] A liquid crystal element provided with the liquid crystal alignment film of the above [2].
[4] A step of forming a photoalignment film by applying the liquid crystal alignment agent of the above [1] to each substrate surface of a pair of substrates and irradiating the substrate surfaces with light, and the liquid crystal alignment film are formed. A method for manufacturing a liquid crystal element, which comprises a step of arranging a pair of substrates so that the photoalignment films face each other with a liquid crystal layer interposed therebetween to construct a liquid crystal cell.
[5] A step of applying the liquid crystal aligning agent of the above [1] on each of the conductive films of a pair of substrates having a conductive film to form a coating film, and a pair of substrates on which the coating film is formed. A liquid crystal display including a step of constructing a liquid crystal cell by arranging the coating films so as to face each other across the liquid crystal layer, and a step of irradiating the liquid crystal cell with light while a voltage is applied between the conductive films. Method of manufacturing the element.

According to the liquid crystal alignment agent of the present disclosure, a liquid crystal element having excellent light resistance and heat resistance can be obtained by containing the cyclic siloxane compound [A] together with the polymer component.

≪Liquid crystal alignment agent≫
The liquid crystal alignment agent of the present disclosure contains a polymer component and an additive component. Further, as an additive component, a cyclic siloxane compound [A] having a crosslinkable group is contained. Hereinafter, each component contained in the liquid crystal alignment agent and other components optionally blended will be described.

In addition, in this specification, a "hydrocarbon group" means a chain hydrocarbon group, an alicyclic hydrocarbon group and an aromatic hydrocarbon group. The "chain hydrocarbon group" means a linear hydrocarbon group and a branched hydrocarbon group which do not contain a cyclic structure in the main chain and are composed only of a chain structure. However, it may be saturated or unsaturated. The "alicyclic hydrocarbon group" means a hydrocarbon group containing only the alicyclic hydrocarbon structure as the ring structure and not containing the aromatic ring structure. However, it does not have to be composed only of the alicyclic hydrocarbon structure, and some of them have a chain structure. The "aromatic hydrocarbon group" means a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it does not have to be composed of only an aromatic ring structure, and a chain structure or an alicyclic hydrocarbon structure may be included in a part thereof.

<Polymer component>
The polymer component contained in the liquid crystal alignment agent is crosslinked by the cyclic siloxane compound [A]. The type of the main skeleton of the polymer component is not particularly limited. Specific examples of the polymer component include polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, polyester, polyamide, polyamideimide, polystyrene, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, polymaleimide, and the like. Examples thereof include a styrene-maleimide-based copolymer or a polymer having a poly (meth) acrylate as a main skeleton. In addition, (meth) acrylate means containing acrylate and methacrylate.

Among these, the polymer components include a point that the cross-linking reaction with the cyclic siloxane compound [A] is easily promoted, a point that the compatibility with the cyclic siloxane compound [A] is better, and a cyclic siloxane compound [A]. Derived from polyamic acid, polyamic acid ester, polyimide, and a monomer having a polymerizable unsaturated bond in that a liquid crystal element having a high effect of improving heat resistance and having higher reliability can be obtained when used in combination with It is preferably at least one selected from the group consisting of polymers having structural units. The polymer component has a functional group capable of reacting with the crosslinkable group of the cyclic siloxane compound [A] (hereinafter, also referred to as “reactive functional group”). The reactive functional group can be appropriately designed according to the crosslinkable group of the cyclic siloxane compound [A]. Hereinafter, preferred examples of the polymer components will be described.

(Polyamic acid)
The polyamic acid can be obtained by reacting a tetracarboxylic dianhydride with a diamine compound.
-Tetracarboxylic dianhydride Examples of the tetracarboxylic dianhydride used for the synthesis of polyamic acid include aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and aromatic tetracarboxylic dianhydride. You can mention things. Specific examples of these include, for example, 1,2,3,4-butanetetracarboxylic dianhydride as the aliphatic tetracarboxylic dianhydride;
As the alicyclic tetracarboxylic acid dianhydride, for example, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentylacetic hydride, 5- (2,5-dioxo tetrahydrofuran-3-yl) -3a, 4,5,9b-tetrahydronaphtho [1,2-c] furan-1 , 3-Dione, 5- (2,5-dioxo tetrahydrofuran-3-yl) -8-methyl-3a, 4,5,9b-Tetrahydronaphtho [1,2-c] furan-1,3-dione, 2,4,6,8-Tetracarboxybicyclo [3.3.0] Octane-2: 4,6: 8-dianhydride, cyclopentanetetracarboxylic acid dianhydride, cyclohexanetetracarboxylic acid dianhydride, etc. As aromatic tetracarboxylic dianhydride, for example, pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, ethylene glycol bisanhydrotrimate, 4,4'-(hexa). Fluoroisopropylidene) diphthalic anhydride, 4,4'-carbonyldiphthalic anhydride and the like can be mentioned, respectively, and the tetracarboxylic dianhydride described in JP-A-2010-97188 can be used. can. As the tetracarboxylic dianhydride, one type can be used alone or two or more types can be used in combination.

（式（Ｅ−１）中、Ｘ^I及びＸ^IIは、それぞれ独立に、単結合、−Ｏ−、＊−ＣＯＯ−又は＊−ＯＣＯ−（ただし、「＊」はＸ^Ｉとの結合手を示す。）であり、Ｒ^Ｉは炭素数１〜３のアルカンジイル基であり、Ｒ^ＩＩは単結合又は炭素数１〜３のアルカンジイル基であり、ａは０又は１であり、ｂは０〜２の整数であり、ｃは１〜２０の整数であり、ｄは０又は１である。但し、ａ及びｂが同時に０になることはない。）
で表される化合物等の側鎖型ジアミン：-Diamine compound Examples of the diamine compound used for the synthesis of polyamic acid include aliphatic diamines, alicyclic diamines, aromatic diamines, and diaminoorganosiloxane. Specific examples of these diamines include metaxylylenediamine, 1,3-propanediamine, hexamethylenediamine and the like as aliphatic diamines; 1,4-diaminocyclohexane and 4,4'-methylenebis as alicyclic diamines. (Cyclohexylamine) etc .;
As aromatic diamines, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, octadecanoxy-2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5 -Diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, 3,5-diaminobenzoate Ranostanate acid, 3,6-bis (4-aminobenzoyloxy) cholesterol, 3,6-bis (4-aminophenoxy) cholesterol, 2,4-diamino-N, N-diallylaniline, 4- (4'-tri) Fluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-butylcyclohexane, 3,5-diaminobenzoic acid = 5ξ-cholestane- 3-Il, a diamine having a cyclic carbonate group in the side chain, a diamine having a (meth) acryloyl group in the side chain, the following formula (E-1).

(In the formula (E-1), X ^I and X ^II are independently single-bonded, -O-, * -COO- or * -OCO- (where "*" is a bond with ^{X I.} shown.), and, ^{R I} is an alkanediyl group having 1 to 3 carbon ^{atoms, R II} is a single bond or an alkanediyl group having 1 to 3 carbon atoms, a is 0 or 1, b is 0 It is an integer of ~ 2, c is an integer of 1 to 20, d is 0 or 1. However, a and b cannot be 0 at the same time.)
Side chain diamines such as compounds represented by:

p-Phenylenediamine, 4,4'-diaminodiphenylmethane, 4-aminophenyl-4-aminobenzoate, 4,4'-diaminoazobenzene, 3,5-diaminobenzoic acid, 1,5-bis (4-aminophenoxy) Pentan, 1,2-bis (4-aminophenoxy) ethane, bis [2- (4-aminophenyl) ethyl] hexanedioic acid, N, N-bis (4-aminophenyl) methylamine, 1,4-bis -(4-Aminophenyl) -piperazin, N, N'-bis (4-aminophenyl) -benzidine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis (trifluoromethyl) ) -4,4'-Diaminobiphenyl, 4,4'-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis (4-aminophenyl) hexafluoropropane , 4,4'-(phenylenediisopropyridene) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-[4,4 '-Propane-1,3-diylbis (piperidin-1,4-diyl)] dianiline, 4,4'-diaminobenzanilide, 4,4'-diaminostylbenzene, 4,4'-diaminodiphenylamine, 1,3 -Bis (4-aminophenethyl) urea, 1,3-bis (4-aminobenzyl) urea, 1,4-bis (4-aminophenyl) -piperazin, N- (4-aminophenylethyl) -N-methyl Main chain diamines such as amine, N, N'-bis (4-aminophenyl) -N, N'-dimethylbenzidine, etc .; as diaminoorganosiloxane, for example, 1,3-bis (3-aminopropyl)- In addition to each of tetramethyldisiloxane and the like, the diamine described in JP-A-2010-97188 can be used.

-Synthesis of polyamic acid A polyamic acid can be obtained by reacting a tetracarboxylic dianhydride and a diamine compound with a molecular weight modifier (for example, acid monoanhydride, monoamine, etc.), if necessary. The ratio of the tetracarboxylic dianhydride and the diamine compound used in the polyamic acid synthesis reaction is 0.2 to 0.2 to 1 equivalent of the amino group of the diamine compound. A ratio of 2 equivalents is preferable.

The polyamic acid synthesis reaction is preferably carried out in an organic solvent. The reaction temperature at this time is preferably −20 ° C. to 150 ° C., and the reaction time is preferably 0.1 to 24 hours. Examples of the organic solvent used in the reaction include an aprotic polar solvent, a phenolic solvent, an alcohol, a ketone, an ester, an ether, a halogenated hydrocarbon, and a hydrocarbon. Particularly preferred organic solvents are N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol. And one or more selected from the group consisting of halogenated phenol can be used as a solvent, or a mixture of one or more of these with another organic solvent (for example, butyl cellosolve, diethylene glycol diethyl ether, etc.) can be used. preferable. The amount of the organic solvent used (a) shall be such that the total amount (b) of the tetracarboxylic dianhydride and the diamine is 0.1 to 50% by mass with respect to the total amount (a + b) of the reaction solution. Is preferable.

(Polyamic acid ester)
The polyamic acid ester is, for example, [I] a method of reacting the polyamic acid obtained by the above synthetic reaction with an esterifying agent, [II] a method of reacting a tetracarboxylic acid diester with a diamine compound, and [III] a tetracarboxylic. It can be obtained by a method of reacting an acid diester dihalide with a diamine compound, or the like. The polyamic acid ester contained in the liquid crystal alignment agent may have only an amic acid ester structure, or may be a partial esterified product in which the amic acid structure and the amic acid ester structure coexist.

(Polyimide)
The polyimide can be obtained, for example, by dehydrating and ring-closing the polyamic acid synthesized as described above to imidize it. From the viewpoint of sufficiently carrying out the crosslinking reaction with the cyclic siloxane compound [A], the polyimide has a preferably imidization ratio of 20 to 99%, more preferably 30 to 90%. The imidization ratio is a percentage of the number of imide ring structures to the total of the number of amic acid structures and the number of imide ring structures of polyimide. A part of the imide ring may be an isoimide ring.

The dehydration ring closure of a polyamic acid is preferably carried out by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration ring closure catalyst to this solution, and heating as necessary. In this method, examples of the dehydrating agent include acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride. The amount of the dehydrating agent used is preferably 0.01 to 20 mol with respect to 1 mol of the amic acid structure of the polyamic acid. As the dehydration ring closure catalyst, for example, tertiary amines such as pyridine, collagen, lutidine, and triethylamine can be used. The amount of the dehydration ring closure catalyst used is preferably 0.01 to 10 mol with respect to 1 mol of the dehydrating agent used. Examples of the organic solvent used in the dehydration ring closure reaction include organic solvents exemplified as those used in the synthesis of polyamic acids. The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C. The reaction time is preferably 1.0 to 120 hours.

(Polymer having a structural unit derived from a monomer having a polymerizable unsaturated bond)
Examples of the polymer having a structural unit derived from a monomer having a polymerizable unsaturated bond (hereinafter, also referred to as “polymer [Pm]”) include a (meth) acrylic compound as a monomer having a polymerizable unsaturated bond. , Polymers (poly (meth) acrylate, styrene-maleimide-based copolymer, polystyrene, polymaleimide) obtained by using one or more of the maleimide compound and the styrene compound can be mentioned. The polymer [Pm] is preferably composed of a poly (meth) acrylate and a styrene-maleimide-based copolymer because it is easy to introduce an orientation group and the reliability of the obtained liquid crystal element is better. At least one selected from the group. When the polymer [Pm] is a styrene-maleimide-based copolymer, the copolymer further has a structural unit derived from a monomer different from the styrene compound and the maleimide compound (for example, a (meth) acrylic compound, etc.). May be.

In the present specification, the "oriented group" is a group capable of imparting a pretilt angle to liquid crystal molecules in the liquid crystal layer when the liquid crystal alignment film is arranged adjacent to the liquid crystal layer. Specific examples thereof include a group capable of imparting a pretilt angle to a liquid crystal molecule without light irradiation (hereinafter, also referred to as a “vertically oriented group”), and a photooriented group. Specific examples of the vertically oriented group include an alkyl group having 4 to 20 carbon atoms, an alkoxy group having 4 to 20 carbon atoms, a fluoroalkyl group having 4 to 20 carbon atoms, and a fluoroalkoxy group having 4 to 20 carbon atoms. Two or more rings (preferably at least one ring selected from the group consisting of cyclohexane ring, benzene ring and naphthalene ring) are direct or divalent linking groups (eg, oxygen atom, -CO- or -COO-). Examples thereof include a group having a mesogen structure formed by binding via, a group having a steroid skeleton, and the like.

The monomer used for the synthesis of the polymer [Pm] is not particularly limited as long as it has a polymerizable unsaturated bond, and is, for example, a (meth) acryloyl group, a vinyl group, a styryl group, a vinylphenyl group, a maleimide group, or the like. Examples thereof include compounds having a polymerizable unsaturated bond of. Specific examples of these compounds include unsaturated carboxylic acids such as (meth) acrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, and vinyl benzoic acid: alkyl (meth) acrylic acid (eg, (meth) acrylic). Methyl acrylate, -2-ethylhexyl (meth) acrylate, etc.), Cycloalkyl (meth) acrylate, benzyl (meth) acrylate, trimethoxysilylpropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, Unsaturated carboxylic acid esters such as glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxybutyl (meth) acrylate, 4-hydroxybutyl glycidyl ether acrylate: maleine anhydride Unsaturated polyvalent carboxylic acid anhydrides such as acids: (meth) acrylic compounds such as; aromatic vinyl compounds such as styrene, methylstyrene, divinylbenzene, 4- (glycidyloxymethyl) styrene, 4-vinylbenzoic acid; Conjugate diene compounds such as 1,3-butadiene, 2-methyl-1,3-butadiene;
N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, 4- (2,5-dioxo-3-pyrrolin-1-yl) benzoic acid, N- (4-glycidyloxyphenyl) maleimide, N-glycidylmaleimide , 3-Maleimide benzoic acid, 3-Maleimide propionic acid, 3- (2,5-dioxo-3-pyrrolin-1-yl) benzoic acid, 4- (2,5-dioxo-3-pyrrolin-1-yl) Maleimide compounds such as methyl benzoate and the like can be mentioned.

Further, when the polymer [Pm] is a polymer having a photo-oriented group, a compound having a photo-oriented group can also be used as the monomer having a polymerizable unsaturated bond. Specific examples of the compound having a photo-oriented group include a maleimide compound having a cinnamic acid structure, a (meth) acrylic compound having a cinnamic acid structure, and the like. As the monomer having a polymerizable unsaturated bond, one type can be used alone or two or more types can be used in combination. In addition, in this specification, "(meth) acryloyl" means "acryloyl" and "methacryloyl". "(Meta) acrylic" means "acrylol" and "methacryl".

The polymer [Pm] can be obtained, for example, by polymerizing a monomer having a polymerizable unsaturated bond in the presence of a polymerization initiator. The polymerization initiator used is 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2, An azo compound such as 4-dimethylvaleronitrile) is preferred. The ratio of the polymerization initiator used is preferably 0.01 to 30 parts by mass with respect to 100 parts by mass of all the monomers used in the reaction. The polymerization reaction is preferably carried out in an organic solvent. Examples of the organic solvent used in the reaction include alcohols, ethers, ketones, amides, esters, hydrocarbon compounds and the like, and diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether acetate and the like are preferable. The reaction temperature is preferably 30 ° C. to 120 ° C., and the reaction time is preferably 1 to 36 hours. The amount (a) of the organic solvent used should be such that the total amount (b) of the monomers used in the reaction is 0.1 to 60% by mass with respect to the total amount (a + b) of the reaction solution. Is preferable.

For the polymer component, the polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) is preferably 1,500 to 500,000, preferably 2,500 to 100,000. Is more preferable. In the polymerization reaction for obtaining each polymer, when a reaction solution containing the polymer is obtained, the reaction solution may be used as it is for preparation of a liquid crystal aligning agent, or the polymer is isolated and then the liquid crystal is used. It may be used for the preparation of the aligning agent. The method for isolating the polymer is not particularly limited, and the polymer can be isolated according to a known method.

When a liquid crystal alignment ability is imparted to an organic film formed by using a liquid crystal alignment agent by a photoalignment method, it is preferable that at least a part of the polymer component is a polymer having a photoalignment group. The photo-oriented group refers to a functional group capable of imparting anisotropy to the film by a photoreaction such as a photoisomerization reaction, a photodimerization reaction, a photofries rearrangement reaction, or a photodecomposition reaction by light irradiation.

Specific examples of the photo-orientating group include an azobenzene-containing group containing azobenzene or a derivative thereof as a basic skeleton, a lauric acid structure-containing group containing katsura acid or a derivative thereof (a katsura acid structure) as a basic skeleton, a chalcone or a derivative thereof. A chalcone-containing group containing as a basic skeleton, a benzophenone-containing group containing benzophenone or a derivative thereof as a basic skeleton, a coumarin-containing group containing coumarin or a derivative thereof as a basic skeleton, a cyclobutane-containing structure containing cyclobutane or a derivative thereof as a basic skeleton, stillben or Examples thereof include a stillben-containing group having the derivative as a basic skeleton, a phenylbenzoate or a phenylbenzoate-containing group containing the derivative as a basic skeleton. Of these, the photooriented group is preferably at least one selected from the group consisting of an azobenzene-containing group, a cinnamic acid structure-containing group, a chalcone-containing group, a stilbene-containing group, a cyclobutane-containing structure, and a phenylbenzoate-containing group. A stilbene structure-containing group or a cyclobutane-containing structure is preferable because of its high sensitivity to light and easy introduction into the polymer.

The polymer having a photo-oriented group is, for example, (1) a method obtained by polymerization using a monomer having a photo-oriented group, (2) a polymer having an epoxy group in a side chain is synthesized, and the polymer contains the epoxy group. It can be obtained by a method of reacting a polymer with a carboxylic acid having a photo-oriented group, or the like. The content ratio of the photo-oriented group in the polymer is appropriately set according to the type of the photo-oriented group so as to impart the desired liquid crystal alignment ability to the coating film. For example, when the photo-oriented group is a cinnamic acid structure-containing group, the content ratio of the photo-oriented group is preferably 5 mol% or more, preferably 10 to 10%, based on all the constituent units of the polymer having the photo-oriented group. More preferably, it is 60 mol%. When the photo-oriented group has a cyclobutane-containing structure, the content ratio of the photo-oriented group is preferably 50 mol% or more, preferably 80 mol% or more, based on all the constituent units of the polymer having the photo-oriented group. Is more preferable. As the polymer having a photo-oriented group, one type may be used alone, or two or more types may be used in combination.

The polymer component contained in the liquid crystal alignment agent may be one type alone, but is preferably a polymer blend containing two or more types of polymers. In this case, the two or more kinds of polymers may be the same kind of polymer (for example, polyamic acid and polyamic acid), and the types of monomers used may be different from each other, or different kinds of polymers. (For example, polyamic acid and polymethacrylate) may be used. When a cross-linking agent is blended in a polymer blend system, if the dispersibility of the cross-linking agent in the liquid crystal alignment agent is not sufficient, the cross-linking reaction of the polymer by the cross-linking agent is not efficiently performed, and the effect of blending the cross-linking agent is sufficient. There is concern that it cannot be obtained. On the other hand, it is considered that the cyclic siloxane compound [A] has high compatibility with the polymer and high solubility in the solvent, and can be easily dispersed at the cross-linking point of the polymer. As a result, it is presumed that the reaction efficiency of the cross-linking reaction could be increased even when the polymer was blended, and a liquid crystal element having excellent light resistance and heat resistance could be obtained.

As a preferable example of the liquid crystal alignment agent, the liquid crystal alignment agent contains a first polymer and a second polymer having a higher polarity than the first polymer. In this case, it is preferable that the second polymer having high polarity is unevenly distributed in the lower layer and the first polymer is unevenly distributed in the upper layer to cause phase separation. Preferred embodiments of the polymer component of the liquid crystal alignment agent include the following (I) to (III).
(I) An embodiment in which the first polymer and the second polymer are polymers selected from the group consisting of polyamic acids, polyamic acid esters, and polyimides.
(II) An embodiment in which one of the first polymer and the second polymer is a kind of polymer selected from the group consisting of polyamic acid, polyamic acid ester and polyimide, and the other is a polymer [Pm]. ..
(III) An embodiment in which the first polymer and the second polymer are polymers [Pm].

In the above aspect (II), the total content ratio of the polyamic acid, the polyamic acid ester, and the polyimide is contained in the liquid crystal aligning agent from the viewpoint of reducing the cost while sufficiently obtaining the improving effect of the polymer [Pm]. It is preferably 20% by mass or more, more preferably 30% by mass or more, and further preferably 50 to 90% by mass with respect to the total amount of the polymer components. When the liquid crystal alignment ability is imparted to an organic film formed by using a liquid crystal alignment agent by a photo-alignment method, the liquid crystal orientation is high by using a polymer [Pm] as a polymer having a photo-orientation group. It is preferable in that an alignment film can be obtained.

The content ratio of the polymer component in the liquid crystal alignment agent is the total mass of solids contained in the liquid crystal alignment agent (total mass of components other than the solvent of the liquid crystal alignment agent) from the viewpoint of sufficiently increasing the film strength. On the other hand, it is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more.

<Cyclic siloxane compound [A]>
The cyclic siloxane compound [A] is a cyclic compound having one cyclic skeleton in the molecule due to a siloxane bond (Si—O bond), and has a crosslinkable group. The crosslinkable group is not particularly limited as long as it can form a crosslinked structure by covalently bonding with another group, but for example, an oxylanyl group, an oxetanyl group, a (meth) acryloyl group, an allyl group, a vinylphenyl group, or a cyclic group. Examples thereof include a carbonate group, a methylol group and an amino group. The crosslinkable group is preferably at least one selected from the group consisting of an oxylanyl group, an oxetanyl group and a (meth) acryloyl group in that the storage stability of the liquid crystal alignment agent can be improved, and the oxylanyl group is particularly preferable. In addition, in this specification, "(meth) acryloyl" means to include "acryloyl" and "methacryloyl".

The number of crosslinkable groups contained in one molecule of the cyclic siloxane compound [A] is preferably 2 or more in that the effect of improving the heat resistance and light resistance of the obtained liquid crystal element can be sufficiently obtained. It is more preferable that the number is 4 or more, and further preferably 4 or more. Further, the number of crosslinkable groups contained in one molecule of the cyclic siloxane compound [A] is formed in that the compatibility with the polymer component is better, the dispersibility in the liquid crystal alignment agent can be improved, and the number of crosslinkable groups is formed. From the viewpoint of suppressing performance deterioration due to film shrinkage of the liquid crystal alignment film, the number is preferably 10 or less, and more preferably 8 or less.

When a liquid crystal alignment film is formed using a liquid crystal alignment agent, the crosslinkable group of the cyclic siloxane compound [A] reacts with the reactive functional group of the polymer component by heating during film formation to form a crosslinked structure. Is formed. The combination of the crosslinkable group and the reactive functional group is appropriately selected depending on the storage stability, the ease of introduction into the polymer, the reactivity to heat or light, and the like. Specifically, when the crosslinkable group is an epoxy group, examples of the reactive functional group include a carboxyl group, a hydroxyl group, and an amino group, and the carboxyl group is preferable in that the storage stability is good. .. When the crosslinkable group is a (meth) acryloyl group, examples of the reactive functional group include a thiol group and a (meth) acryloyl group. When the crosslinkable group is a vinyl group, examples of the reactive functional group include a thiol group and a vinyl group. When the crosslinkable group is an amino group, the reactive functional group includes a carboxyl group, a hydroxyl group and an epoxy. Groups, halogen atoms and the like can be mentioned. When the crosslinkable group is a cyclic carbonate group, examples of the reactive functional group include an amino group, a hydroxyl group, a carboxyl group, an epoxy group and an acid anhydride group, and when the crosslinkable group is a methylol group, the reactive functional group Examples of the group include an epoxy group, an amino group, a hydroxyl group, a carboxyl group and the like. However, the combination is not limited to these.

（式（１）中、Ｒ^１〜Ｒ^６は、それぞれ独立して、水素原子又は炭素数１〜２０の１価の有機基である。ただし、Ｒ^１〜Ｒ^６のうち少なくとも１個は、架橋性基を有する１価の有機基である。ｎは１〜１８の整数である。ｎが２以上の場合、複数のＲ^１は互いに同じでも異なっていてもよく、複数のＲ^２は互いに同じでも異なっていてもよい。）The cyclic siloxane compound [A] is preferably a compound represented by the following formula (1).

(In the formula (1), R ^{1 to} R ⁶ are independently hydrogen atoms or monovalent organic groups having 1 to 20 carbon atoms. However, at least one of ^{R 1 to} R ^{6 is.} is a monovalent organic group having a crosslinkable group .n If it .n is 2 or more 1-18 integer multiple of R ¹ may be the same as or different from each other, a plurality of R ² are each It may be the same or different.)

In the above formula (1), when R ^{1 to} R ⁶ are monovalent organic groups, specific examples thereof include a monovalent hydrocarbon group having 1 to 20 carbon atoms and at least one of the monovalent hydrocarbon groups. -O-, -COO-, -S-, -NR between the carbon-carbon bonds of a monovalent group Q1 in which one hydrogen atom is replaced with a crosslinkable group and a hydrocarbon group having 2 to 20 carbon atoms. ¹⁰ - or ^-CONR 10 - ^{(. R 10} is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms) monovalent group Q2 having, at least one of the monovalent group Q2 Examples thereof include a group Q3 in which a hydrogen atom is replaced with a crosslinkable group, and these groups may have a substituent. Examples of the substituent include a hydroxyl group and a halogen atom. When R ^{1 to} R ⁶ are monovalent hydrocarbon groups, the monovalent hydrocarbon group is preferably an alkyl group, an alkenyl group or a phenyl group, and more preferably an alkyl group.
R ^{1 to} R ⁶ are carbons in that the dispersibility of the cyclic siloxane compound [A] in the liquid crystal aligning agent can be improved, and the compatibility with the polymer component and the solubility in the solvent can be improved. It is preferably a monovalent organic group having a number of 1 to 20, and preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent group Q1, a monovalent group Q2, or a monovalent group Q3. More preferred. The carbon number of R ^{1 to} R ⁶ is preferably 1 to 15, more preferably 1 to 10.

When R ^{1 to} R ⁶ are monovalent organic groups having a crosslinkable group, the monovalent organic group having a crosslinkable group is preferably a group represented by the following formula (2).
* ^1- R ^7- X ¹ ... (2)
(In the formula (2), R ⁷ is a divalent group having a chain structure, X ¹ is a monovalent group having a crosslinkable group, and "* ¹ " is a bond with a silicon atom. Represents that.)

In the above formula (2), ^{the chain structure of R 7} is preferably −O— or − between carbon-carbon bonds of an alkanediyl group having 1 to 10 carbon atoms or an alkanediyl group having 2 to 10 carbon atoms. It is a divalent group having S- and may have a substituent. Examples of the substituent include a hydroxyl group and a halogen atom. The carbon number of R ⁷ is preferably 1 to 7, and more preferably 2 to 5.
X ¹ is preferably a monovalent group having an oxylanyl group, an oxetanyl group, a (meth) acryloyl group, an allyl group, a vinylphenyl group, a cyclic carbonate group, a methylol group or an amino group, and is stable for storage of a liquid crystal aligning agent. From the viewpoint of sex, it is more preferably a monovalent group having an oxylanyl group, an oxetanyl group or a (meth) acryloyl group, and particularly preferably a monovalent group having an epoxy group (oxylanyl group or an oxetanyl group). .. Examples of the monovalent group having an epoxy group include an epoxy group, a glycidyloxy group, an epoxycyclohexyl group and the like.

Of the two monovalent groups bonded to the silicon atom in the above formula (1), at least one (R ¹ , R ³ and R ⁵ ) is a group represented by the above formula (2), and the other (R 1, R 5) is (2). R ^2, it is preferred that ^{R 4} and ^{R 6)} is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^{2, R 4} and ^{R 6,} more preferably an alkyl group having 1 to 5 carbon atoms, more preferably methyl group or an ethyl group.
n is preferably 1 to 10 and is preferably 1 to 6 from the viewpoint of dispersibility of the cyclic siloxane compound [A] in the liquid crystal alignment agent, compatibility with the polymer component, and availability of the material. It is more preferable, and it is particularly preferable that it is 1 to 4.

The cyclic siloxane compound [A] may further have a photoreactive group. Since the cyclic siloxane compound [A] has a photoreactive group, it can cause self-crosslinking due to a thermal reaction of the photoreactive group, and when a liquid crystal element is obtained by PSA treatment, it has the same light resistance as the crosslinkable group. And heat resistance can be obtained, which is preferable. The photoreactive group is preferably a group having a carbon-carbon unsaturated bond, and examples thereof include a (meth) acryloyl group, a vinylphenyl group, and a vinyl group. Of these, the (meth) acryloyl group is particularly preferable because it has high photoreactivity and easily causes self-crosslinking due to a thermal reaction of the photoreactive group. The photoreactive group is a functional group that does not cause a cross-linking reaction with the reactive functional group introduced into the polymer component in order to cross-link the polymer component with the cyclic siloxane compound [A].

When the cyclic siloxane compound [A] has a photoreactive group, the crosslinkable group of the cyclic siloxane compound [A] is preferably a group having no polymerizable unsaturated bond, specifically an epoxy group. , Amino group, cyclic carbonate group, methylol group and the like. When the cyclic siloxane compound [A] has a photoreactive group, the number of photoreactive groups is preferably 1 or more, and more preferably 2 or more. Further, the number of photoreactive groups is preferably 4 or less, and preferably 2 or less, in order to sufficiently secure the number of crosslinkable groups introduced.

The molecular weight of the cyclic siloxane compound [A] ensures sufficient dispersion in the liquid crystal alignment agent, better compatibility with the polymer component and better solubility in the solvent, and sufficient film strength of the liquid crystal alignment film. It is preferably less than 1000, more preferably 900 or less, and even more preferably 800 or less. The molecular weight of the cyclic siloxane compound [A] is preferably 100 or more, and more preferably 200 or more, from the viewpoint of suppressing the volatilization of the cyclic siloxane compound [A].

（式（Ａ−１）〜（Ａ−７）中、Ｒは水素原子又はメチル基であり、ｎは０〜１８の整数である。）Specific examples of the cyclic siloxane compound [A] include compounds represented by the following formulas (A-1) to (A-10). A commercially available product may be used as the cyclic siloxane compound [A]. Examples of commercially available products include CS-697, CS-783 (above, manufactured by Sigma-Aldrich), KR-470, X-40-2670, X-40-2678 (above, manufactured by Shin-Etsu Silicone Co., Ltd.) and the like. ..

(In formulas (A-1) to (A-7), R is a hydrogen atom or a methyl group, and n is an integer from 0 to 18.)

The content ratio of the cyclic siloxane compound [A] is 100 parts by mass, which is the total amount of the polymer components contained in the liquid crystal aligning agent, in that the effect of improving the light resistance and heat resistance of the obtained liquid crystal element can be sufficiently increased. On the other hand, it is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, and further preferably 0.1 part by mass or more. The content ratio of the cyclic siloxane compound [A] is 40% by mass with respect to 100 parts by mass of the total amount of the polymer components contained in the liquid crystal alignment agent in that film shrinkage during formation of the liquid crystal alignment film can be suppressed. It is preferably parts or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. As the cyclic siloxane compound [A], one type may be used alone, or two or more types may be used in combination.

<Other ingredients>
The liquid crystal alignment agent of the present disclosure may contain a polymer component and other compounds other than the cyclic siloxane compound [A], if necessary. Specific examples thereof include, for example, epoxy compounds (for example, N, N, N', N'-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N. , N, N', N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N, N-diglycidyl-aminomethylcyclohexane, 1,6-hexanediol di (meth) acrylate, pentaerythritol tri (meth) acrylate, etc. ), Functional silane compounds (eg, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, etc.), antioxidants, metal chelate compounds, curing accelerators, surfactants. Examples include agents, fillers, dispersants, photosensitizers and the like. The blending ratio of the other compounds can be appropriately selected according to each compound within a range that does not impair the effects of the present disclosure.
When a compound different from the cyclic siloxane compound [A] is used in combination as the cross-linking agent, the content ratio of the compound is 5% by mass with respect to the total amount of the cyclic siloxane compound [A] contained in the liquid crystal alignment agent. % Or less, more preferably 1% by mass or less.

-Solvent component The liquid crystal alignment agent of the present disclosure is prepared as a solution-like composition in which a polymer component, a cyclic siloxane compound [A], and a component arbitrarily blended as necessary are preferably dissolved in an organic solvent. Will be done. Examples of the organic solvent include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons and the like. The solvent component may be one of these or a mixed solvent of two or more.

As the solvent component, a solvent having high solubility and leveling property of the polymer (hereinafter, also referred to as “first solvent”), a solvent having good wettability and spreading property (hereinafter, also referred to as “second solvent”), and a solvent component. Examples thereof include a mixed solvent of these.
Specific examples of the solvent include, for example, N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N, N-dimethylformamide, N, N-dimethylacetamide, 4-hydroxy-4-methyl as the first solvent. -2-Pentanone, diisobutylketone, ethylene carbonate, propylene carbonate, N-ethyl-2-pyrrolidone, N- (n-pentyl) -2-pyrrolidone, N- (t-butyl) -2-pyrrolidone, N-methoxypropyl -2-Pyrrolidone, 1,3-dimethyl-2-imidazolidinone, 3-butoxy-N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, etc.;
As the second solvent, for example, ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diacetone alcohol, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, propylene glycol monomethyl Ether, propylene glycol monomethyl ether acetate, 3-methoxy-1-butanol, cyclopentanone, butyl lactate, butyl acetate, methylmethoxypropionate, ethylethoxypropionate, isoamylpropionate, isoamylisobutyrate, Examples thereof include propylene glycol diacetate, dipropylene glycol monomethyl ether, propylene glycol monobutyl ether, diisopentyl ether and the like. The solvent may be one of these alone, but is preferably a mixed solvent of the first solvent and the second solvent.

The solid content concentration in the liquid crystal alignment agent (the ratio of the total mass of the components other than the solvent of the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) is appropriately selected in consideration of viscosity, volatility, etc., but is preferable. It is in the range of 1 to 10% by mass. When the solid content concentration is less than 1% by mass, the film thickness of the coating film becomes too small and it becomes difficult to obtain a good liquid crystal alignment film. On the other hand, when the solid content concentration exceeds 10% by mass, the film thickness of the coating film becomes excessive and it is difficult to obtain a good liquid crystal alignment film, and the viscosity of the liquid crystal alignment agent increases and the coatability deteriorates. There is a tendency.

≪Liquid crystal alignment film and liquid crystal element≫
The liquid crystal alignment film of the present disclosure is formed by the liquid crystal alignment agent prepared as described above. Further, the liquid crystal element of the present disclosure includes a liquid crystal alignment film formed by using the liquid crystal alignment agent described above. The operation mode of the liquid crystal in the liquid crystal element is not particularly limited, and for example, TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.), IPS (In-Plane Switching) type, FFS (Fringe). It can be applied to various modes such as Field Switching) type, OCB (Optically Compensated Bend) type, and PSA type (Polymer Sustained Alignment). The liquid crystal element can be manufactured, for example, by a method including the following steps 1 to 3. In step 1, the substrate used differs depending on the desired operation mode. Steps 2 and 3 are common to each operation mode.

<Step 1: Formation of coating film>
First, a liquid crystal alignment agent is applied to each substrate surface of the pair of substrates, and preferably the coated surface is heated to form a coating film on the substrate. As the substrate, for example, glass such as float glass and soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, and poly (aliphatic olefin) can be used. As the transparent conductive film provided on one surface of the substrate, NESA film (US PPG registered trademark) made of tin oxide (SnO _2), indium oxide - ITO made of tin oxide _{(In 2} O 3 -SnO ₂₎ film Etc. can be used. When manufacturing a TN type, STN type or VA type liquid crystal element, two substrates provided with a patterned transparent conductive film are used. On the other hand, in the case of manufacturing an IPS type or FFS type liquid crystal element, a substrate provided with electrodes patterned in a comb tooth shape and an opposed substrate not provided with electrodes are used. The liquid crystal alignment agent is applied to the substrate by an offset printing method, a flexographic printing method, a spin coating method, a roll coater method, or an inkjet printing method, preferably on the electrode forming surface.

After the liquid crystal alignment agent is applied, preheating is preferably performed for the purpose of preventing the applied liquid crystal alignment agent from dripping. The pre-baking temperature is preferably 30 to 200 ° C., and the pre-baking time is preferably 0.25 to 10 minutes. Then, a firing (post-baking) step is carried out for the purpose of completely removing the solvent and, if necessary, thermally imidizing the amic acid structure in the polymer component. The firing temperature (post-baking temperature) at this time is preferably 80 to 250 ° C, more preferably 80 to 200 ° C. The post-bake time is preferably 5 to 200 minutes. The thickness (thickness) of the film thus formed is preferably 0.001 to 1 μm.

<Step 2: Orientation treatment>
When manufacturing a TN type, STN type, IPS type or FFS type liquid crystal element, a treatment (alignment treatment) for imparting a liquid crystal alignment ability to the coating film formed in the above step 1 is performed. As a result, the alignment ability of the liquid crystal molecules is imparted to the coating film to form a liquid crystal alignment film. As the orientation treatment, a rubbing treatment is performed in which the coating film formed on the substrate is rubbed in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, and cotton, and the coating film formed on the substrate is irradiated with light. It is possible to use a photo-alignment treatment or the like to impart a liquid crystal alignment ability to the coating film to form a photo-alignment film. On the other hand, in the case of manufacturing a vertically oriented (VA) type liquid crystal element, the coating film formed in the above step 1 can be used as it is as a liquid crystal alignment film, but in order to further enhance the liquid crystal alignment ability, the coating film is used. It is advisable to apply an orientation treatment to the film. A liquid crystal alignment film suitable for a vertically oriented liquid crystal element can also be suitably used for a PSA type liquid crystal element.

In the photoalignment treatment, the light irradiation includes a method of irradiating the coating film after the post-baking step, a method of irradiating the coating film after the pre-baking step and before the post-baking step, a pre-baking step and a post-baking step. At least one of them can be carried out by a method of irradiating the coating film while heating the coating film, or the like. As the radiation to irradiate the coating film, for example, ultraviolet rays including light having a wavelength of 150 to 800 nm and visible light can be used. Preferably, it is ultraviolet light containing light having a wavelength of 200 to 400 nm. When the radiation is polarized, it may be linearly polarized or partially polarized. When the radiation used is linearly polarized light or partially polarized light, the irradiation may be performed from a direction perpendicular to the substrate surface, may be performed from an oblique direction, or may be performed in combination thereof. In the case of unpolarized radiation, the irradiation direction is diagonal.

Examples of the light source used include a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excima laser, and the like. The irradiation amount of radiation on the substrate surface is preferably 400 to 50,000 J / m ² , and more preferably 1,000 to 20,000 J / m ² . After light irradiation for imparting orientation ability, the surface of the substrate is washed with, for example, water, an organic solvent (for example, methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.) or a mixture thereof. Or a process of heating the substrate may be performed.

<Step 3: Construction of LCD cell>
Two substrates on which the liquid crystal alignment film is formed as described above are prepared, and the liquid crystal cell is manufactured so that the liquid crystal is arranged adjacent to the liquid crystal alignment film between the two substrates. In order to manufacture a liquid crystal cell, for example, two substrates are arranged to face each other with a gap so that the liquid crystal alignment films face each other, and the peripheral portions of the two substrates are bonded with a sealant, and the substrate surface and the sealant are attached. Examples thereof include a method of injecting and filling a liquid crystal display in a cell gap surrounded by, and sealing the injection hole, a method of using the ODF method, and the like. As the sealing agent, for example, an epoxy resin containing an aluminum oxide sphere as a curing agent and a spacer can be used. Examples of the liquid crystal include a nematic liquid crystal and a smectic liquid crystal, and among them, the nematic liquid crystal is preferable. In the PSA mode, after the liquid crystal cell is constructed, the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of the pair of substrates.

When manufacturing a PSA type liquid crystal element, a liquid crystal cell is constructed in the same manner as described above except that a photopolymerizable monomer is injected or dropped together with the liquid crystal between a pair of substrates having a conductive film. As the photopolymerizable monomer, a conventionally known compound can be used. Preferably, it is a polyfunctional (meth) acrylic monomer. Then, the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of the pair of substrates. The voltage applied here can be, for example, 5 to 50 V DC or AC. Further, as the light to be irradiated, for example, ultraviolet rays including light having a wavelength of 150 to 800 nm and visible light can be used. Of these, ultraviolet rays containing light having a wavelength of 300 to 400 nm are preferable. As the light source of the irradiation light, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excima laser, or the like can be used. The irradiation amount of light is preferably 1,000 to 200,000 J / m ² , and more preferably 1,000 to 150,000 J / m ² .

Subsequently, if necessary, a polarizing plate is attached to the outer surface of the liquid crystal cell to form a liquid crystal element. Examples of the polarizing plate include a polarizing plate in which a polarizing film called "H film" in which polyvinyl alcohol is stretch-oriented and iodine is absorbed is sandwiched between cellulose acetate protective films, or a polarizing plate made of the H film itself.

The liquid crystal elements of the present disclosure can be effectively applied to various applications, for example, clocks, portable games, word processors, notebook computers, car navigation systems, camcoders, PDAs, digital cameras, mobile phones, smartphones, various monitors. It can be applied to various display devices such as liquid crystal televisions and information displays, dimming films, retardation films, and the like.

Hereinafter, the present disclosure will be specifically described with reference to Examples, but the present disclosure is not limited to the following Examples.
In the following examples, the solution viscosity, weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw / Mn), imidization ratio and epoxy equivalent of the polymer were measured by the following methods.
<Solution viscosity of polymer>
The solution viscosity of the polymer was measured at 25 ° C. using an E-type viscometer.
<Weight average molecular weight, number average molecular weight and molecular weight distribution>
Mw and Mn were measured by gel permeation chromatography (GPC) under the following conditions. The molecular weight distribution (Mw / Mn) was calculated from the obtained Mw and Mn.
Equipment: Showa Denko Corporation "GPC-101"
GPC column: Combines "GPC-KF-801", "GPC-KF-802", "GPC-KF-803" and "GPC-KF-804" manufactured by Shimadzu GLC Co., Ltd. Mobile phase: tetrahydrofuran (THF) )
Column temperature: 40 ° C
Flow velocity: 1.0 mL / min Sample concentration: 1.0 mass%
Sample injection volume: 100 μL
Detector: Differential refractometer Standard substance: Monodisperse polystyrene <Imidization rate of polymer>
A solution containing polyimide is put into pure water, the obtained precipitate is sufficiently dried under reduced pressure at room temperature, dissolved in deuterated dimethyl sulfoxide, and ¹ H-NMR is measured at room temperature using tetramethylsilane as a reference substance. bottom. From the obtained ¹ H-NMR spectrum, the imidization ratio was determined using the following mathematical formula (E-1).
Imidization rate (%) = (1-A ¹ / A ² x α) x 100 ... (E-1)
(In the formula (E-1), A ¹ is the peak area derived from the proton of the NH group appearing near the chemical shift of 10 ppm, A ² is the peak area derived from the other protons, and α is the precursor of the polymer (α). Polyamic acid) is the ratio of the number of other protons to one proton of the NH group.)
<Epoxy equivalent>
The epoxy equivalent was measured by the hydrochloric acid-methylethylketone method described in JIS C 2105.

The abbreviations of the compounds used in the examples below are shown below. In the following, for convenience, the "compound represented by the formula (X)" may be simply referred to as "compound (X)".

-Cyclic siloxane compound [A]

-Other than cyclic siloxane compound [A]

<Synthesis of polymer>
[Synthesis Example 2-1: Polyimide Synthesis]
77 g (0.34 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride, and 19 g (0.18 mol) of p-phenylenediamine and 27 g of 3,5-diaminobenzoic acid as diamine. (0.18 mol) was dissolved in 1,260 g of N-methyl-2-pyrrolidone (NMP) and reacted at room temperature for 6 hours to obtain a solution containing a polyamic acid. A small amount of the obtained polyamic acid solution was taken and concentrated under reduced pressure to obtain a solution having a concentration of 10% by mass, and the solution viscosity was 80 mPa · s. Next, 600 g of NMP was added to the obtained polyamic acid solution, 136 g of pyridine and 105 g of acetic anhydride were added, and a dehydration ring closure reaction was carried out at 110 ° C. for 4 hours. After the dehydration ring closure reaction, the solvent in the system is replaced with a new γ-butyrolactone, and the solution is further concentrated to contain 20% by mass of the polymer (PI-1) which is a polyimide having an imidization ratio of about 85%. 600 g was obtained. A small amount of this solution was taken, γ-butyrolactone was added, and the solution was measured as a solution having a concentration of 6.0% by mass. The solution viscosity was 22 mPa · s.

[Synthesis Example 2-2: Synthesis of polyamic acid]
1,2,3,4-cyclobutanetetracarboxylic dianhydride as tetracarboxylic dianhydride 13.8 g (0.070 mol), 2,2'-dimethyl-4,4'-diaminobiphenyl 16.3 g as diamine (0.0769 mol) was dissolved in 170 g of NMP and reacted at 25 ° C. for 3 hours to obtain a solution containing 10% by mass of polyamic acid (referred to as "polymer (PA-1)"). ..

[Synthesis Example 2-3: Synthesis of Styrene-Maleimide Copolymer]
In a 100 mL two-necked flask under nitrogen, as a polymerization monomer, 5.00 g (8.6 mmol) of compound (MI-1), 0.64 g (4.3 mmol) of 4-vinylbenzoic acid, 4- (2,5-dioxo). 2.82 g (13.0 mmol) of -3-pyrrolin-1-yl) benzoic acid, 3.29 g (17.2 mmol) of 4- (glycidyloxymethyl) styrene, and 2,2'-azobis (17.2 mmol) as a radical polymerization initiator. Add 0.31 g (1.3 mmol) of 2,4-dimethylvaleronitrile, 0.52 g (2.2 mmol) of 2,4-diphenyl-4-methyl-1-pentene as the chain transfer agent, and 25 ml of tetrahydrofuran as the solvent. , 70 ° C. for 5 hours. After reprecipitation in n-hexane, the precipitate was filtered and vacuum dried at room temperature for 8 hours to obtain a polymer (StMI-A) which is a styrene-maleimide-based copolymer. The weight average molecular weight Mw measured by GPC in terms of polystyrene was 30,000, and the molecular weight distribution Mw / Mn was 2.

[Synthesis Example 2-4: Synthesis of Styrene-Maleimide Copolymer]
In Synthesis Example 2-3, polymerization was carried out in the same manner as in Synthesis Example 2-3 except that the compound (MI-2) was used instead of the compound (MI-1) as the polymerization monomer. After reprecipitation in n-hexane, the precipitate was filtered and vacuum dried at room temperature for 8 hours to obtain a polymer (StMI-B) which is a styrene-maleimide-based copolymer. The weight average molecular weight Mw measured by GPC in terms of polystyrene was 25,000, and the molecular weight distribution Mw / Mn was 2.

[Synthesis Example 2-5: Synthesis of Epoxy Group-Containing Polyorganosiloxane]
A reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser was charged with 100.0 g of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 500 g of methylisobutylketone, and 10.0 g of triethylamine. Mix at room temperature. 100 g of deionized water was added dropwise thereto from a dropping funnel over 30 minutes, and then the reaction was carried out at 80 ° C. for 6 hours while mixing under reflux. After completion of the reaction, the organic layer was taken out, washed with a 0.2 mass% ammonium nitrate aqueous solution until the water after washing became neutral, and then the solvent and water were distilled off under reduced pressure to obtain an epoxy group-containing poly. Organosiloxane was obtained as a viscous clear liquid. The epoxy equivalent of this epoxy group-containing polyorganosiloxane (referred to as "polyorganosiloxane (PS-1)") was measured and found to be 186 g / equivalent.

<Preparation and evaluation of liquid crystal alignment agent>
[Example 1]
1. 1. Preparation of liquid crystal alignment agent (AL-1) The polymer (StMI-A) obtained in Synthesis Example 2-3 was added to a solution containing 100 parts by mass of the polymer (PI-1) obtained in Synthesis Example 2-1. 10 parts by mass, 2 parts by mass of compound (A-1-1) (trade name "KR-470", manufactured by Shinetsu Silicone Co., Ltd.), and NMP and butyl cellosolve (BC) were added as solvents, and the solvent composition was NMP / BC = 50. A solution having a solid content concentration of / 50 (mass ratio) and a solid content concentration of 4.0% by mass was prepared. A liquid crystal alignment agent (AL-1) was prepared by filtering this solution through a filter having a pore size of 1 μm.

2. Manufacture of Optical Vertical Liquid Crystal Display Element The liquid crystal alignment agent (AL-1) prepared above is applied to the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film using a spinner, and a hot plate at 80 ° C. is applied. Pre-baked for 1 minute. Then, the inside of the oven was heated at 230 ° C. for 1 hour in a nitrogen-substituted oven to form a coating film having a film thickness of 0.1 μm. ^{Next, the surface of the coating film was irradiated with polarized ultraviolet rays of 1,000 J / m 2} containing a bright line of 313 nm from a direction inclined by 40 ° with respect to the substrate normal using an Hg-Xe lamp and a Gran Tailor prism. The coating film was imparted with a liquid crystal alignment ability. The same operation was repeated to prepare a pair (two sheets) of substrates having a liquid crystal alignment film.
An epoxy resin adhesive containing aluminum oxide spheres having a diameter of 3.5 μm was applied by screen printing to the outer periphery of the surface having the liquid crystal alignment film on one of the pair of substrates on which the liquid crystal alignment film was formed. Subsequently, the liquid crystal alignment film surfaces of the pair of substrates are opposed to each other, crimped so that the projection directions of the optical axes of the ultraviolet rays of each substrate are antiparallel, and the adhesive is heated at 150 ° C. for 1 hour. It was cured. Next, a negative liquid crystal display (MLC-6608, manufactured by Merck Co., Ltd.) was filled in the gap between the substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive. Further, in order to remove the flow orientation at the time of liquid crystal injection, this was heated at 130 ° C. and then slowly cooled to room temperature to obtain a liquid crystal cell. Next, polarizing plates are attached to both outer surfaces of the substrate so that their polarization directions are orthogonal to each other and the direction of projection of the ultraviolet rays of the liquid crystal alignment film on the substrate surface is 45 °. Manufactured an optical vertical liquid crystal display element.

3. 3. Evaluation of Liquid Crystal Display Element The above operation was repeated to manufacture a plurality of liquid crystal display elements, and the following heat resistance and light resistance were evaluated. The heat resistance and light resistance were evaluated using separate liquid crystal display elements.
[Evaluation of heat resistance]
After applying a voltage of 5 V at 60 ° C. for an application time of 60 microseconds and a span of 167 ms to the optical vertical liquid crystal display element manufactured above, the voltage retention rate 167 ms after the application was released was measured. This was defined as the initial voltage retention rate Arf [%]. Next, the liquid crystal cell was allowed to stand in an oven at 100 ° C. for 1,000 hours to apply thermal stress, and then the voltage retention rate was measured again under the same conditions, and the voltage retention rate after thermal stress Atm [%] was measured. And said. The amount of decrease α [%] (α = Arf-Atm) of the voltage retention rate Atm after thermal stress with respect to the initial voltage retention rate Arf was calculated, and the heat resistance of the liquid crystal display element was evaluated by the amount of decrease α. When the amount of decrease α is 1% or less, the heat resistance is "extremely good (◎)", and when the amount of decrease α is more than 1% and 2% or less, the heat resistance is "good (○)". When the amount α was more than 2% and 3% or less, the heat resistance was evaluated as “possible (Δ)”, and when the amount of decrease α was more than 3%, the heat resistance was evaluated as “poor (×)”. As a result, the heat resistance was evaluated as "extremely good (⊚)" in this example. A VHR-1 manufactured by Toyo Corporation was used as the voltage holding rate measuring device.

[Evaluation of light resistance]
The voltage holding ratio of the optical vertical liquid crystal display element manufactured above was measured under the same conditions as the evaluation of heat resistance, and this was defined as the initial voltage holding ratio Arf [%]. Next, the liquid crystal display element was allowed to stand at a distance of 5 cm under a 0-watt white fluorescent lamp, irradiated with light for 1,000 hours to apply light stress, and then the voltage retention rate was measured again under the same conditions. Was defined as the voltage retention rate after light stress Agt [%]. The amount of decrease β [%] (β = Arf-Agt) in the voltage retention rate after light stress with respect to the initial voltage retention rate Arf was calculated, and the light resistance of the liquid crystal display element was evaluated by the amount of decrease β. When the amount of decrease β is 1% or less, the light resistance is “extremely good (⊚)”, and when the amount of decrease β is more than 1% and 2% or less, the light resistance is “good (○)” and is reduced. When the amount β exceeded 2% and was 3% or less, the light resistance was evaluated as “possible (Δ)”, and when the amount of decrease β exceeded 3%, the light resistance was evaluated as “poor (×)”. As a result, in this example, the light resistance was evaluated as "extremely good (⊚)".

[Examples 2 to 9 and Comparative Examples 1, 2, 4, 6]
A liquid crystal alignment agent was prepared with the same solvent composition and solid content concentration as in Example 1 except that the compounding composition was changed as shown in Tables 1 to 3 below. Further, an optical vertical liquid crystal display element was manufactured in the same manner as in Example 1 using each liquid crystal alignment agent, and various evaluations were performed. The results are shown in Tables 1 to 3 below.

[Example 10]
1. 1. Preparation of liquid crystal alignment agent (AL-10) The polymer to be used is a solution containing 100 parts by mass of the polymer (PA-1) obtained in Synthesis Example 2-2, and a weight obtained in Synthesis Example 2-4. A liquid crystal aligning agent (AL-10) was prepared with the same solvent composition and solid content concentration as in Example 1 above except that the mixture (StMI-B) was changed to 5 parts by mass.

2. Preparation of liquid crystal composition With respect to 10 g of nematic liquid crystal (MLC-6608 manufactured by Merck Co., Ltd.), 5% by mass of the liquid crystal compound represented by the above formula (L1-1) and the above formula (L2-1) are represented. The liquid crystal composition LC1 was obtained by adding 0.3% by mass of the photopolymerizable compound and mixing the compounds.

3. 3. Manufacture of PSA-type liquid crystal display element A liquid crystal alignment film printing machine (Nissha Printing Co., Ltd.) is applied on each electrode surface of two glass substrates each having a conductive film made of ITO electrodes by applying the liquid crystal alignment agent (AL-10) prepared above. Apply using (manufactured by Co., Ltd.), heat (pre-bake) for 2 minutes on a hot plate at 80 ° C to remove the solvent, and then heat (post-bake) for 10 minutes on a hot plate at 230 ° C to average. A coating film having a thickness of 0.06 μm was formed. These coating films were ultrasonically cleaned in ultrapure water for 1 minute and then dried in a 100 ° C. clean oven for 10 minutes to obtain a pair (2 sheets) of substrates having a liquid crystal alignment film. The electrode pattern used is the same as the electrode pattern in the PSA mode.
Next, an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm is applied to the outer edge of the surface of one of the pair of substrates having the liquid crystal alignment film, and then the liquid crystal alignment film surfaces are overlapped so as to face each other. Together, they were crimped to cure the adhesive. Next, a liquid crystal cell was manufactured by filling the liquid crystal composition LC1 prepared above between the pair of substrates from the liquid crystal injection port and then sealing the liquid crystal injection port with an acrylic photocurable adhesive. After that, an AC 10V having a frequency of 60 Hz is applied between the conductive films of the liquid crystal cell, and while the liquid crystal is being driven, an irradiation amount of ^{100,000 J / m 2 is used using an ultraviolet irradiation device using a metal halide lamp as a light source.} Was irradiated with ultraviolet rays. The irradiation amount is a value measured using a photometer measured based on a wavelength of 365 nm. After that, polarizing plates are attached to both outer surfaces of the substrate so that their polarization directions are orthogonal to each other and the direction of projection of the optical axis of the liquid crystal alignment film on the substrate surface is 45 °. A PSA type liquid crystal display element was manufactured.

4. Evaluation of Liquid Crystal Display Element The above operation was repeated to manufacture a plurality of liquid crystal display elements, and the heat resistance and light resistance were evaluated in the same manner as in Example 1. As a result, in this example, both heat resistance and light resistance were evaluated as "extremely good (⊚)".

[Examples 11 to 13 and Comparative Examples 3 and 5]
A liquid crystal alignment agent was prepared with the same solvent composition and solid content concentration as in Example 10 except that the compounding composition was changed as shown in Tables 2 and 3 below. Further, a PSA type liquid crystal display element was manufactured in the same manner as in Example 10 using each liquid crystal alignment agent, and various evaluations were performed in the same manner as in Example 1. The results are shown in Tables 2 and 3 below.

In Tables 1 to 3, "-" indicates that the compound in the corresponding column was not used. The abbreviations of the compounds are as follows.
A-1-1: Product name "KR-470", manufactured by Shin-Etsu Silicone Co., Ltd. (compound represented by the above formula (A-1-1))
A-2-1: Product name "CS-697", manufactured by Sigma-Aldrich (compound represented by the above formula (A-2-1))
A-3-1: Product name "CS-783", manufactured by Sigma-Aldrich (compound represented by the above formula (A-3-1))
C-1: Product name "X-40-2669", manufactured by Shin-Etsu Silicone Co., Ltd. (compound represented by the above formula (C-1))
C-2: Polyorganosiloxane (PS-1) of Synthesis Example 2-5 above
C-3: N, N, N', N'-tetraglycidyl-4,4'-diaminodiphenylmethane (compound represented by the above formula (C-3))

From the above results, in Examples 1 to 13 in which the liquid crystal alignment agent containing the cyclic siloxane compound [A] was used as the cross-linking agent, the evaluation of the heat resistance and light resistance of the liquid crystal display element was "extremely good (⊚)" or The result was "good (○)".
On the other hand, in Comparative Examples 4 and 5 having the same composition as the liquid crystal alignment agents of Examples 1 to 3 and Examples 10 to 13 except that the cyclic siloxane compound [A] was not contained, the light resistance was higher than that of the examples. And both heat resistance was inferior.
Further, in Comparative Example 1 in which the compound (C-1) which is a polyfunctional siloxane compound having a chain structure was used instead of the cyclic siloxane compound [A], the light resistance was higher than that in Examples (Examples 1 to 3). Was inferior, and the heat resistance was also inferior to Examples 1 and 2. In Comparative Examples 2 and 3 in which polyorganosiloxane (PS-1) was used instead of the cyclic siloxane compound [A], light resistance and heat resistance were higher than those in Examples (Examples 1 to 3 and Examples 10 to 13). Both were inferior.
In addition, Comparative Example 6 using the conventionally used cross-linking agent compound (C-3) was also inferior in both light resistance and heat resistance as compared with Examples.
From these results, it was found that a liquid crystal device having excellent heat resistance and light resistance can be obtained by using the cyclic siloxane compound [A] as the cross-linking agent.

Claims (8)

A liquid crystal alignment agent containing a polymer component and a cyclic siloxane compound [A] having a crosslinkable group. The liquid crystal alignment agent according to claim 1, wherein the cyclic siloxane compound [A] is a compound represented by the following formula (1).

(In the formula (1), R ^{1 to} R ⁶ are independently hydrogen atoms or monovalent organic groups having 1 to 20 carbon atoms. However, at least one of ^{R 1 to} R ^{6 is.} is a monovalent organic group having a crosslinkable group .n If it .n is 2 or more 1-18 integer multiple of R ¹ may be the same as or different from each other, a plurality of R ² are each It may be the same or different.) The polymer component is at least one selected from the group consisting of a polymer having a structural unit derived from a polyamic acid, a polyamic acid ester, a polyimide, and a monomer having a polymerizable unsaturated bond, according to claim 1 or 2. The liquid crystal alignment agent described. The liquid crystal alignment agent according to any one of claims 1 to 3, which contains two or more kinds of polymers as the polymer component. A liquid crystal alignment film formed by using the liquid crystal alignment agent according to any one of claims 1 to 4. A liquid crystal element comprising the liquid crystal alignment film according to claim 5. A step of applying the liquid crystal alignment agent according to any one of claims 1 to 4 to each substrate surface of a pair of substrates and irradiating the substrate surfaces with light to form a photoalignment film.
A step of constructing a liquid crystal cell by arranging a pair of substrates on which the liquid crystal alignment film is formed so that the photoalignment films face each other with the liquid crystal layer interposed therebetween.
A method for manufacturing a liquid crystal element, including. A step of applying the liquid crystal alignment agent according to any one of claims 1 to 4 onto each of the conductive films of a pair of substrates having a conductive film to form a coating film.
A step of constructing a liquid crystal cell by arranging a pair of substrates on which the coating film is formed so that the coating films face each other with a liquid crystal layer interposed therebetween.
A step of irradiating the liquid crystal cell with light while a voltage is applied between the conductive films,
A method for manufacturing a liquid crystal element, including.